Intelligent remarks. Let's not forget also that yooung English players are priced highly to discourage demand. The spending power of premiership clubs in general is much greater than that of lower leageus. Why then shouldn't lower league clubs demand more for their key players who will leave a massive hole in the side after their departure? They have premiership ambitions and know they must be able to purchase players of that standard in order to compete.
In contrast, the next Ivory Coast starlet will be worth much less because his club doesn't need x amount of cash in order to be competitive in their league.
So by that way of thinking the lower league club can replace their lost player with the Ivory coast player (who would probably be better than the homegrown one) for a low price. Hell with the amount of money they'd make selling the "English" player they could probably be able to buy three Ivory coast players each with twice the skill of the one they sold.